Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 6. (Budapest 1955)
Halász, M.: The characteristic occurrences of blue green algae in the hot springs of Harkány
height of 3,5 m at the point of its eruption. Its water volume per 24 hours is about 3,682 hi. (Zsigmondy recorded 29,000 kh) 4 . In the thermal springs of Harkány, as in hot springs generally, the Cyanophyceae build their formation corresponding to the equalization of the environmental conditions at the place of the ascension of the water : in the oecologically different zones (Schwabe, 1949). Advancing up to the outflow of the thermal water, the phytocoenologically well distinguishable and clearly differentiated Cyanophyceae associations form elliptical rings in the basin of the spring (Halász, 1949). These associations, with regard to their characteristical and dominant species, compose closed communities .The stability of some of them is the more worthy of notice as they can be observed in certain other aero- and euthermal groups of the Central Danubian Basin, and they show the same form of appearance. By their occurrences, they give a specia lbiological character to the groups of hot springs, which could, otherwise, not be separated chemically from each other. More than one characteristical association is to be observed in our home thermae. Most characteristical among them is the association of Mastigocladus laminosus (Halász, 1953), philogenetically very early and morphologically extremely rich and varying. The characteristic element of this association is the primeval alga species, Mastigocladus laminosus, belonging, in every probability, to that group of algae which may be regarded as relict organisms, that is, primitive plant species surviving from the earliest geological periods to the present day, and representing possibly one of the types of the ancient vegetation of the Earth (M i h o 1 i c, 1935; Voronihin, 1929). It is a more important fact, however, that the occurrences of this bluegreen alga with its connected associations are linked up with certain conditions which we are unable as yet to interprète in the biology of thermae. Notably, it is a striking fact that whilst it occurs in some of thesprings of identical temperature and chemical composition, it is absent in others (V o u k, 1938; Halász, 1949 b; 1953; Kol, 1932, 1952). This ancient association type constitutes both pure and mixed communities in the zones of the highest temperatures at the outflow of the spring water in the therma of Harkány (Halász, 1949 a). The associations evolved on the inner surfaces of the well are, as it happens, of an antagonistical development. On the borderline areas, transitional zones are formed in which the dominant species of the associations of the adjoining zones are present in about equal numbers. As the temperature of the zones, retreating from the ascending spring water, gradually decreases concurrently with the decrease of also the amount of water, the pure associations of Mastigocladus pass over into a mixed association whose characteristical species, besides Mastigocladus, is Symploca thermalis (Kütz.) Gom. This blue-green alga, being a typical pyrophyte (V o u k, 1937 a), tends to settle on the surrounding stones of the spring and on the walls steeped by the hot vapours ; its pure associations may also be found in their most beautiful forms of appearance in these places. 4 Report of the expert of the Ministry of Agriculture, 1 December, 1891, by J. Mattyasovszky.
